Needles to create pneumoperitoneum are used to insufflate the abdominal cavity to facilitate endoscopic examination and surgery. A Verress-type pneumoneedle has a spring-loaded, blunt tipped inner needle contained within a larger diameter piercing needle. The larger diameter needle is hollow and allows for passage of the blunt needle therein. Once the Verress-type needle penetrates the abdominal wall, and enters the body cavity, the resistance against the end of the Verress-type needle is removed, so that the spring force causes the blunt needle to move forward, to extend beyond the sharp tip of the outer needle. This allows the needle to enter the body without puncture or laceration of any abdominal structures.
Verress-type needles use a hollow, blunt inner needle capable of fluid passage, and to carry insufflating gas into the abdominal cavity. A stopcock and valve assembly is connected to the inner needle. The inner needle and valve assemblies are pushed rearward by resistance on the needle end and are biased forward by a spring when the resistance is removed. With this type of design, the needle is grasped like a dart, or in some instances, along outer flanges, like a surgical trocar. In creating these designs, however, it has been found that there are certain perceived drawbacks to these needles.
First, it is difficult to know when the needle is fully inserted into the body. Consequently, there is no visual or audible means to know that: (a) the hollow sharpened outer needle has pierced the peritoneum; (b) the blunt inner needle is no longer rectracted due to a resistant force; or (c) the blunt inner needle has been pushed forward by a preloaded spring, so that it again protects the instrument from damaging any internal organs.
The lack of these functions may cause uncertainty during use of current Verress-type needles.